Deployment

The first section tells you how many machines you need. The second explains how to bootstrap bookies
(BookKeeper storage servers). The third section explains how we use ZooKeeper and our requirements with
respect to ZooKeeper.

System requirements

A typical BookKeeper installation comprises a set of bookies and a set of ZooKeeper replicas. The exact number of bookies
depends on the quorum mode, desired throughput, and number of clients using this installation simultaneously. The minimum number of
bookies is three for self-verifying (stores a message authentication code along with each entry) and four for generic (does not
store a message authentication codewith each entry), and there is no upper limit on the number of bookies. Increasing the number of
bookies, in fact, enables higher throughput.

For performance, we require each server to have at least two disks. It is possible to run a bookie with a single disk, but
performance will be significantly lower in this case. Of course, it works with one disk, but performance is significantly lower.

For ZooKeeper, there is no constraint with respect to the number of replicas. Having a single machine running ZooKeeper
in standalone mode is sufficient for BookKeeper. For resilience purposes, it might be a good idea to run ZooKeeper in quorum
mode with multiple servers. Please refer to the ZooKeeper documentation for detail on how to configure ZooKeeper with multiple
replicas

Ideally, /path_to_log_device/ and /path_to_ledger_device/ are each
in a different device.

ZooKeeper Metadata

For BookKeeper, we require a ZooKeeper installation to store metadata, and to pass the list
of ZooKeeper servers as parameter to the constructor of the BookKeeper class (
org.apache.bookkeeper.client,BookKeeper).
To setup ZooKeeper, please check the
ZooKeeper documentation.